SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '93b8f6f05800574f85312f06902232eae265751f668fd625f50c8ceb539da90a' 
  AND token = 'v+Bx8dW7Gs5n5laUJNhVCYn4sTlmBKGrrHiwJHBO+iw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}